Mobile communications networks typically utilize a plurality of base stations to connect user terminals to a wireless network. Each of the user terminals communicates with a base station to exchange information with the wireless network when located in a cell area serviced by the base station. The base station transmits backhaul data back and forth with a core network via a backhaul link.
The transmission of backhaul data via wired connections is expensive and can cause delay in wireless development. Wireless backhaul, on the other hand, typically uses separate time/frequency resources from those of the wireless data such as, e.g., an alternate system offering services on a different bandwidth allocation. These separate resources, however, may not be available or offer an acceptable range/quality such as, e.g., unlicensed spectrum.
There are systems in the art in which communication on the same time-frequency resources can be achieved via spatial separation with an antenna array, a practice known as Spatial Division Multiple Access (“SDMA”). In SDMA, an antenna array forms multiple spatial channels to allow several communication links to share the same time frequency resources. A receive antenna array employs multiple receive beamformers, each arranged to receive one communication link, while spatially suppressing the other communication links. Similarly, a transmit antenna array employs multiple transmit beamformers, each arranged to transmit one communication link towards its intended recipient while transmitting it away from other receivers through transmit spatial nulling.
There are wireless backhaul systems in the art that handle the use of backhaul communications by using backhaul repeaters in communication with one or more base stations to forward backhaul communications from the base station(s) to a backhaul access point, and the multiple backhaul links share the same time frequency resources via the practice of SDMA. These systems, however, utilize separate frequency resources for backhaul and for normal wireless data communications. In cellular systems in the initial phase of deployment, such backhaul systems may not be usable because the separate time-frequency resources may not be available.
There are wireless cellular systems in the art that employ SDMA to enable multiple wireless data communication links between wireless users and a base station to share the same time-frequency resources. However, the backhaul traffic for these systems is either handled with wired links (which can prevent rapid network deployment) or use wireless backhaul links on a different spectral allocations (which in some cases might be unavailable) or steal time-frequency resources from the wireless data traffic (which severely reduces network efficiency). Accordingly, current wireless systems are complex and inefficient.
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